There is nothing new in there being negative political ads in the US.
People often refer back to a famous television spot put together by Lyndon B Johnson campaign in 1964 called "Daisy".
It showed a two-year-old girl picking flowers when, suddenly, an ominous voice commences a missile launch countdown. There is a flash and a mushroom cloud from a nuclear explosion. It was a response to Johnston’s opponent Barry Goldwater suggesting nuclear weapons could be used in Vietnam.
It aired only once, but was credited with helping Johnson to a landslide win.
Yet negative ads go back almost to the beginning of political campaigning in the US.
In 1828, supporters of John Quincy Adams issued handbills which called Andrew Jackson's mother a prostitute and accused his wife of committing adultery.
Willie Horton ad
The first negative radio ad aired in 1936, and, of course, there was the infamous Willie Horton ad in 1988, in which Democratic candidate Michael Dukakis was accused of giving weekend parole passes to killers and one of them, while released, killed again.
The ad had a huge impact, and helped George HW Bush to win the presidency.
Now, Mitt Romney is airing an ad which claims Barack Obama has gone too far with his attacks.
Called "America Deserves Better", it criticises a controversial TV ad from an Obama-supporting Political Action Committee (PAC) that claimed that a man called Joe Soptic lost his wife to cancer after Romney's old firm, Bain Capital, shut down the factory where he worked, costing Soptic his health insurance.
The ad is deeply cynical. It fails to mention Romney was not working at Bain when the plant was closed that even though Scoptic lost his health insurance, his wife remained covered through her own job and it was five years after the plant was closed that she was diagnosed with cancer.
Even by American political standards, the ad is ruthless, and it has attracted widespread criticism.
The Obama campaign has not condemned the ad or asked that it be pulled. But it's hardly surprising.
The president and his senior advisers are from Chicago, hardly known for its genteel and polite political discourse.
Remember, this was a campaign which ploughed into Hillary Clinton during the primaries and suggested her husband was a racist. Romney's argument is that the US deserves better from its president.
Yet for Romney to complain is almost as staggering. He has courted the support of billionaire Donald Trump, who has been at the forefront of the campaign suggesting Obama was not born in the US and, by extension, is not qualified to be president.
Others in his party have tried to suggest Obama is a closet Muslim, while Congresswoman Michelle Bachmann alleged one of Clinton's top aides was a secret Muslim Brotherhood agent.
Romney has not disavowed either idea.
Paroxysms of rage
Romney and his supporters also spent millions first smearing Newt Gingrich and then Rick Santorum during the primary campaign, sending both into paroxysms of rage and envy, because they couldn’t afford to match his attacks.
Romney himself has sought to distort an Obama statement about small businesses, claiming the president said that entrepreneurs did not build their businesses, when what Obama had really said was that they had built those businesses with the help of crucial infrastructure like roads.
Despite the high-minded ideals that both sides always proclaim at the start of a campaign, this has become one of the dirtiest campaigns in American history.
Neither party can claim the moral high ground.
What is sad is that negative campaigning sticks. Research in the Journal of Advertising found that while negative advertising makes people want to physically turn away, the mind remembers the negative messages.
Both sides are ready to set aside their principles to win. The voters are the losers.
Follow Alan Fisher on Twitter @alanfisher